Switch user(su) two times Post: 302519449

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Operating Systems AIX Switch user(su) two times Post 302519449 by bakunin on Wednesday 4th of May 2011 03:32:13 AM

05-04-2011

Registered User

Quote:

Originally Posted by mtwain

ABC is an account which has sugroups=su2DEF and root is not part of su2DEF group.

Your question has already been answered by the others, but I'd like to comment on your scenario: root doesn't have to be in this group because for practial purposes root is per definition in every group there is: root can read/write any file or directory regardless of being in that particular group or not, because the normal group rights won't apply to root (to be precise: the user with UID=0).

What i want to say is: do you really need to switch away from root, given this information?

You might want to do it because the user you switch to is an application user with a very specific environment (databases often have such users) which root lacks. You also might want to do it because the process you start as this user creates some file(s) and you want these files owned by the user, not by root.

Therefore, you still might have a good reason to "su" away from root, but you might want to reestimate the need to so in light of above information.

BTW: you can su to another user for a single command with the "-c" switch. For instance:

Code:

#! /bin/ksh

# this script is started by root

/some/command_to_run_as_root

su - user1 -c /some/where/script_to_run_as_user1.sh
su - user2 -c /some/where/script_to_run_as_user2.sh

/some/other_command_to_run_as_root

exit

I hope this helps.

bakunin

Last edited by bakunin; 05-04-2011 at 04:37 AM..

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LEARN ABOUT LINUX

pam_wheel

PAM_WHEEL(8)							 Linux-PAM Manual						      PAM_WHEEL(8)

NAME

       pam_wheel - Only permit root access to members of group wheel

SYNOPSIS

       pam_wheel.so [debug] [deny] [group=name] [root_only] [trust]

DESCRIPTION

       The pam_wheel PAM module is used to enforce the so-called wheel group. By default it permits root access to the system if the applicant
       user is a member of the wheel group. If no group with this name exist, the module is using the group with the group-ID 0.

OPTIONS

       debug
	   Print debug information.

       deny
	   Reverse the sense of the auth operation: if the user is trying to get UID 0 access and is a member of the wheel group (or the group of
	   the group option), deny access. Conversely, if the user is not in the group, return PAM_IGNORE (unless trust was also specified, in
	   which case we return PAM_SUCCESS).

       group=name
	   Instead of checking the wheel or GID 0 groups, use the name group to perform the authentication.

       root_only
	   The check for wheel membership is done only.

       trust
	   The pam_wheel module will return PAM_SUCCESS instead of PAM_IGNORE if the user is a member of the wheel group (thus with a little play
	   stacking the modules the wheel members may be able to su to root without being prompted for a passwd).

MODULE TYPES PROVIDED

       The auth and account module types are provided.

RETURN VALUES

       PAM_AUTH_ERR
	   Authentication failure.

       PAM_BUF_ERR
	   Memory buffer error.

       PAM_IGNORE
	   The return value should be ignored by PAM dispatch.

       PAM_PERM_DENY
	   Permission denied.

       PAM_SERVICE_ERR
	   Cannot determine the user name.

       PAM_SUCCESS
	   Success.

       PAM_USER_UNKNOWN
	   User not known.

EXAMPLES

       The root account gains access by default (rootok), only wheel members can become root (wheel) but Unix authenticate non-root applicants.

	   su	   auth     sufficient	   pam_rootok.so
	   su	   auth     required	   pam_wheel.so
	   su	   auth     required	   pam_unix.so

SEE ALSO

       pam.conf(5), pam.d(5), pam(7)

AUTHOR

       pam_wheel was written by Cristian Gafton <gafton@redhat.com>.

Linux-PAM Manual						    05/31/2011							      PAM_WHEEL(8)

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